Making a Yeast Starter

Many seasoned homebrewers and professional brewers recommend making yeast starters—especially when using liquid yeasts. Starters build up the population of yeast cells, which leads to a quick start to fermentation. In addition, a larger population ensures the yeast cells don’t get stressed out and produce off-flavors.

About a year ago, I brewed a Rye Pale ale using an expired liquid yeast. I had a delayed (and slow) fermentation and didn’t like the taste of the end result. I think a yeast starter would have been beneficial in this case. So I decided it was finally time to give yeast starters a try.

I wanted to reuse yeast I harvested in August for a Berliner Weisse. My Berliner Weisse recipe called for the same yeast and bacteria strains (European Ale yeast and lactobacillus) that I used in my Sour Cherry Ale. Since the harvested yeast slumbered in my beer fridge for six months, I figured a starter would be the perfect way to liven up the little critters for their next job.

Like most things in the brewing world, a yeast starter can range from complex to simple. I decided to go with the simple method. I’ll eventually get to the stir-plate and online yeast calculators, but baby steps first. Here’s how I made my starter. Be sure to follow the same meticulous sanitation practices used when making beer.

Heat up two cups of water, and slowly stir in one cup of dried golden malt extract.

Add an 1/8 of a teaspoon of yeast nutrient.

Bring the mixture (wort) to a rolling boil, and let it continue to boil for 15 minutes.

Pour the wort into a sanitized Erlenmeyer flask (or glass jar) and immerse it into an ice bath. I used a big pot in my kitchen sink. Beware, regular glass containers can shatter if subjected to extreme temperature differences!

Cool the wort down to a temperature of 70 F.

Vigorously shake the flask to add air to the cooled wort.

Add the liquid yeast and give it another shake.

Cover the flask with a piece of sanitized aluminum foil.

Wait for fermentation to begin. Give the flask a good shake whenever you can.

Apparently, it’s common to see fermentation activity within hours of adding the yeast. Not the case for me. I took nearly two days before the fermentation started. Once it finally kicked in, fermentation completed in about a day. I then put in my refrigerator, which helps the yeast to settle out to the bottom. In the picture below, you can see the layer of white yeast cells on top of the tan layer.

A layer of white yeast cells settling out at the bottom.

When it was time to pitch the yeast into my Berliner Weisse, I decanted the liquid at the top, gave the remaining contents a quick swirl and dumped it into my cooled wort.

How did my first attempt turn out? Quite well, I think. I got the quick fermentation start I wanted and my beer was devoid of off-flavors after primary. So I’ll consider this to be a positive experience. I’ll experiment more with yeast starters—next time with a stir plate!

Do you use yeast starters? What’s your preferred method for making a starter?